Question about bind-dlz performance limit

I'm using bind-dlz(bind version 9.10) with mysql to store zone data. According to‍ the dlz official documents I use the compile arguments " -enable-threads=no‍". Now I use dnstop and netstat to monitor the performance,and find there is a perfomance bottleneck of bind-dlz. Once the QPS increses

Is there any reverse proxy software for dns or udp?

Is there any reverse proxy software for dns‍ , which can do load balance、cache for dns service, just like squid for http service?___ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list bind-users mailing list bi